By Philip Whiteside, international news reporter

In July 2017, the last Islamic State fighters left in the city of Mosul attempted to flee by swimming across the mighty Tigris River that runs through Iraq's second largest city.

They had been defeated.

As patriotic music blared out of portable speaker systems, Iraqi soldiers danced on tanks and re-raised their national flag.

Image:Members of the Iraqi Army with an Islamic State flag, after fighting militants in western Mosul in June 2017

But, as the dust settled and those still in what had become a city of ghosts surveyed the damage caused by the thousands of bombs and millions of bullets used to dislodge IS, the formidable task of rebuilding became clear.

The UK gave £33m in January to help communities in Iraq hit by IS, but as Britain hands out more aid, what is being done to repair and restore the devastated landscape?

The damage

It took nine months for a coalition of Iraqi soldiers, other militia and a US-led task force to dislodge IS from Mosul - a significant part of a longer war to eject the militant group from Iraq.

During nearly four years of conflict between IS and Iraqi forces, the US alone carried out more than 9,000 airstrikes and dropped more than 65,000 bombs as they tried to oust fighters from the towns and cities across the north and west of the country.

Image:A map showing the area that IS ruled at its greatest extent in 2014

The damage to the old city of Mosul alone was estimated at $1bn (£760m). Between 50% and 75% of public buildings in the city of 1.4 million were thought to have been destroyed.

The UN says it has been told of about more than 56,000 dwellings across IS-affected areas, which go far beyond Mosul, that are in need of repairs or replacement.

Of those, 18,000 are in Mosul.

In just the Christian communities on the Nineveh plains, which surround Mosul, around 14,000 homes and 363 churches were damaged or destroyed, according to Christian NGO ACN International.

Image:Destruction in the old city of Mosul. Pic: UN Habitat

In total, five of Iraq's governates - many of them the biggest and most populated - were affected.

It is estimated that almost 8m tonnes of debris was left in Mosul alone by the destruction wreaked during the war.

The people

It is believed about one million of Mosul's inhabitants fled the city during the occupation by IS, also known as Daesh.

Millions more left their homes in other areas in the north and west of Iraq, in fear of what might happen to them.

Among them were Christians, Kurds, Turkmen and Yazidi minorities, many of whom were escaping violent persecution.

Image:The church of Saint Barbara after it was recaptured from Islamic State in Qaragosh

Research by various NGOs has found that people like those who lived under IS rule are afraid to return to their homes, even if they are intact.

The returners

Nearly 90% of those who left Mosul have returned, according to the UN.

Of those, more than half a million school children have been allowed to go back to school after 638 schools reopened - a third of which have been repaired.

Across Iraq, more than four million are said to have gone back home, but there are still well over one million living in temporary shelters.

Image:Women working on a Germany-funded project to repair homes in Sinjar. Pic: UN Habitat

Much of the work undertaken by agencies, including the UN and its partners, has tackled the fears of those communities hardest hit by IS violence - first of all by making their neighbourhoods safe, and then by installing basic services, removing improvised bombs, repairing homes and offering jobs, often on the repair projects.

Rebuilding homes

Work is well under way to repair the damaged homes and communities left shattered by years of occupation and fighting.

But the rate at which it is happening varies.

In Anbar province, the latest UN Habitat report says half of the homes that need repairing have already had the work done.

In Nineveh province, which includes Mosul, progress has been slower. Just over 6,000 out of the 24,000 properties due to be rebuilt or repaired were completed by September 2018, when the last report was released.

The United Nations Development Programme (UNDP), which acts to help countries in need help themselves, said in 2017 that some 10,000 people were employed in rebuilding Mosul.

Several of the people who have been employed in the rebuilding, including major engineering projects, have intentionally been women.

Other buildings

Work has taken place on a host of schools, hospitals and water and electrical facilities across a large swathe of north and west Iraq.

However, many other buildings, including education and health facilities, are still not fully functioning however, leaving many of the region's people unable to access the services others take for granted.

The UN says progress is dependent on funding, with UNDP partnering with the EU and just 25 countries, including the UK and US.

Other repairs are being funded directly by NGOs, with the renovation of churches in particular being carried out by groups like the French Christian NGO Fraternite in Irak.

The group has already restored a tomb at the heart of the Mar Behnam Monastery, one of Syriac Christians' most important shrines, about 32km southeast of Mosul.

Among the areas wrecked by IS fighting was Mosul's old city, which was the heart of the community for millennia.

The World Bank has acknowledged that the preservation of culture is a decisive factor in ensuring communities are rebuilt after conflict. It says an example of how this has been important in the past was the reconstruction of the Stari Most bridge in the Bosnian city of Mostar.

So far UNESCO has only held a series of meetings about its "ReviveTheSpiritOfMosul" project.

Fraternite en Irak's general secretary, Faraj Benoit Camurat, told Sky News projects like the restoration of the Mar Behnam site are critical to helping people recover.

He said:" It is important to find their references, their landmarks, when they come back. Having a house is key to beginning life again, but families also have places where they have 'souvenirs', where they were happy together during important days in life - wedding, baptisms and special events.

Image:A look across the devastated old city of Mosul

"Mar Behnam was quite symbolic of that. It is a key place for Christians from all over Iraq. It's like Notre Dame for French people.

"But, it's also a link for all the communities living in Nineveh because what is quite unique is Ba'aths, Sunnis and Christians come to Mar Behnam and, in a place where Daesh wanted to build [divisions], Mar Behnam allows people to see each other. That's the first step towards reconciliation."

Fraternite en Iraq is now planning to rebuild one of Mosul's oldest churches, the Al Tahira cathedral, which was used as a shooting range by IS, and Mr Camurat says it should take between 12 and 18 months.

Image:The inside of the heavily damaged Syriac Orthodox Al Tahira church in Mosul

Why is progress slow?

NGOs which are contributing to the UN-led effort and the UN itself admit there are a series of issues which have affected progress.

ACT Alliance, an international coalition of Christian church groups and charities which includes Christian Aid, says: "The recovery of Mosul is neighbourhood-specific.

"On the wealthier east side of the Tigris River, recovery has been swift. Restaurants are packed and businesses flourish.

"But in the western portion of Mosul, particularly the old city, block after block of rubbles hide decomposing bodies and unexploded ordnance - the legacy of months of heavy fighting and air strikes as IS fighters made their last stand, often using residents as human shields."

Several groups say the legacy of the IS occupation hangs over Mosul, where many people actually supported the group because of religious affiliations.

Mosul priest Father Amanuel Adel Kloo, who is trying to rebuild his damaged Mosul church, told ACT Alliance: "Daesh isn't gone. There are sleeper cells and fighters who have merely shaved off their beards. The bigger problem is that 70% of the people in Mosul still support the ideology of Daesh. They may not have a weapon in their hands, but they have the mentality of Daesh."

The UN says the speed of progress depends on the scale of the destruction as well as relations with those who liberated the areas previously under IS control.

In Sinjar, where the Yazidi population endured what many claim was an attempt at genocide, UNDP says: "The destruction in Sinjar is almost complete with almost all essential infrastructure having incurred some sort of damage.

"The buildings that remain are contaminated with sophisticated booby traps and IEDs. For these reasons, only approximately 12% of the pre-[IS] population has returned.

"Most of the town, including surrounding villages, does not have access to water... Access to livelihoods remains a critical issue."

Sky News has been told that although the UN has completed the homes it planned to repair in Sinjar, the number it has yet to do so is low because so few people have returned, and many are yet to tell the authorities about work that needs to be done.

In Tel Afar, which has a mostly ethnic Turkmen population, the UN says: "Relations between the community and security forces in control of the town are one of the most pressing impediments to long-term stability in the area.

"To date, only 50% of the population of Tel Afar have returned home. Security concerns are a major deterrent."

According to a report by the Voice of America radio station in December, frustration is growing and leading to the sense of neglect that allowed IS to thrive in the area.

Image:A worker lays paving stones in east Mosul in November 2018

The future

The UN's quarterly report on the progress of what it calls "stabilisation", says: "It is broadly agreed that [the] 1.8 million people who have remained displaced will face more challenges to returning to their areas of origin, an understanding that is well demonstrated by the falling rate of return.

"Whether it be because of lack of basic services, security issues or because of fear of possible reprisals, the effort to facilitate the return of these IDPs, and to ensure protracted displacement does not take place, is one that will require a concentrated effort by the international community.

"All in all, both completed projects and newly started projects demonstrated the overall gains in stabilisation made during the quarter. The falling return rate, however, is demonstrative of the necessity for continued stabilisation efforts.

"As has been communicated before, it is a reality that without additional funding, [the UN] will not be able to continue [the] stabilisation work that it has been undertaking since 2015."